ABSTRACT
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Factors Impacting Root Growth and AM Symbiosis. . . . . . . . . . . . . . . . . . . 146
Soil Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 Soil Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Nutrient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Impacts of Management Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Tillage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Crop Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Inoculum Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 Herbicide and Pesticide Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 Varietal Responses and Breeding Programs . . . . . . . . . . . . . . . . . . . 156 Role of AM Fungi in Soil Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Is Management of AM Fungi Practical? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
INTRODUCTION
Arbuscular mycorrhizal (AM) fungi are recognized as important components of agricultural systems as a consequence of their roles in plant mineral nutrition, root disease dynamics, and soil fertility. While it is generally agreed that AM fungi are a necessary component of agricultural ecosystems, there is only limited understanding as to how to integrate and maintain efficient AM fungi within an annual cropping system. Moreover, our understanding of the
dynamics of AM fungi within an agricultural context applies only to several types of cropping systems under a limited number of climatic conditions. Based on the information that has been collected over the last decade, the importance of AM fungi in various cropping systems is being taken more seriously, particularly as production of some crops moves toward low-input sustainable systems. The importance of AM fungi seems to be more crucial for these low input systems than in the traditional high input production systems, where breeding has selected for genotypes that respond to high fertilizer and water inputs. However, as the cost of chemical inputs and irrigation continues to increase and as researchers assess the sustainability of traditional farming practices, the benefits of AM fungi in an overall crop management plan become economically important.
